1. We investigated the meteorological and hydrological data of past 40 years in Toyama and Gifu prefecture.(1) In winter it has been warm and little snowy for past 10 years. At the stations of plains, change rates (Rf) of total snowfall of one winter (Sf) (Rf=Sf_<max>/Sf_<min>) are 7.0-8.5, and at the the stations of mountainous areas Rf are 2.0-3.0 and it snows steadily there.(2) As mean temparature of winter (Tw) increases by 1ﾟC in plains, Sf decreases by about 160 cm. As Tw approaches 6-7ﾟC,Sf goes to 0 cm aproximately.2. We made a runoff model, and by this model investigated discharges of rivers under the condition of scenarios of global warming (precipitation variation (-10%-+10%) and mean temparature variation (+1ﾟC-4ﾟC)).(1) Effect of global warming differs from characteristics of river basins and snowmelt. The beginning of snowmelt runoff season in spring is advanced for 0.5-2.0 months by global warming.(2) When mean temparature changes by +3ﾟC or more and precipitation change
… Mores by +10%, discharges increase by 50% or more from January to March.3. We analized the corellation between snowfall and water qualities of rivers of Japan, 27 rivers of Toyama prefecture and so on statistically. SS in some rivers increased in snowmelt season, and pH is increasing over a long period time. The increase of snowfall tends to decrease values of pH in rivers.4. We are cbserving dischage and water qualities of a small river, Wadagawa, in Toyama prefecture.(1) Deviding discharges from tank runoff-model into two ones, direct dicharge and indirect discharege, runoff phenomena of electric conductivity can be expressed.(2) Electric conductivity Loading has high correlation with discharge.5. Runoff simulatons of bod-loading were done under the the condition of scenarios of global warming similar to 2.. In result, bod-loading is affected by discharege strongly. For an example, in case that precipitation change is by +10% and mean temparature change by +3ﾟC,it would be 2-5 times from December to February, decrease by 40-60% in spring, and little change in summer and autumn. Less